Commitments and Contingencies - Schedule of Lease Exit Charges and Related Liability Balances (Details) - Lease Exit Costs - USD ($) $ in Thousands	12 Months Ended			36 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2017
Lease Exit Costs
Beginning balance	$ 2,657	$ 1,988
Expense	(133)	3,065	$ 2,200	$ 5,200
Cash Payments	(1,170)	(2,396)
Ending balance	$ 1,354	$ 2,657	$ 1,988	$ 1,354